Environmental Factors in Autism

Abstract

Autism is a neurodevelopmental disorders characterized by impairments in communication and social behavior, and by repetitive behaviors. Although genetic factors might be largely responsible for the occurrence of autism they cannot fully account for all cases and it is likely that in addition to a certain combination of autism-related genes, specific environmental factors might act as risk factors triggering the development of autism. Thus, the role of environmental factors in autism is an important area of research and recent data will be discussed in this review. Interestingly, the results show that many environmental risk factors are interrelated and their identification and comparison might unveil a common scheme of alterations on a contextual as well as molecular level. For example, both, disruption in the immune system and in zinc homeostasis may affect synaptic transmission in autism. Thus, here, a model is proposed that interconnects the most important and scientifically recognized environmental factors. Moreover, similarities in how these risk factors impact synapse function are discussed and a possible influence on an already well described genetic pathway leading to the development of autism via zinc homeostasis is proposed.

Zinc Inhibits Hedgehog Autoprocessing

“…ASD, with an astounding prevalence of ϳ2% (43), is characterized by abnormal social interaction, communication, and stereotyped behaviors in affected children. The etiology of ASD is poorly understood, but both oxidative stress (44) and low zinc status have been reproducibly associated with ASD (16,45). In astrocyte culture, Hh autoprocessing is promoted by H 2 O 2 and low zinc level ( Fig.…”

Vitamin D deficiency and autism; a review on recent findings

“…As mentioned above autism could be due to gestational and early childhood vitamin D inadequacy (60)(61)(62)(63)(64)(65)(66)(67)(68). This situation may be an iatrogenic inadequacy as a result of medical cautions to prevent the sun exposure that unfortunately unsuccessful to compensate for the subsequent epidemic of vitamin D inadequacy (3)(4)(5)(6)(7)(8)(9)61). Recently much attention has been made toward the role of vitamin D in health benefits beyond its effects on bone mineralization.…”

“…ASDs are a heterogeneous group of complex biological and neurodevelopment diseases (1)(2)(3). ASD, with an unknown etiology, remains poorly understood and has no specific treatment.…”

Oxidative Stress and Dietary Interventions in Autism: Exploring the Role of Zinc, Antioxidant Enzymes and Other Micronutrients in the Neurobiology of Autism

“…Zinc deficient animals display an increased susceptibility to exogenous oxidative stress such as endotoxin exposure and hyperoxia [92] and zinc is thought to protect macromolecules such as proteins, lipids and DNA from oxidative damage. Mice defective in CuZnSOD develop neurological damage and cancer at an accelerated rate as they age [16]. Zinc depletion affects the expression of metallothioneins that are low-molecular-weight proteins with high cysteine content and high affinity for metal ions [93].…”

“…and increased vulnerability. There is evidence that many interrelated environmental factors may act as risk factors to development of autism [16].…”